pamstretch(1) - phpMan

pamstretch(1)                        General Commands Manual                        pamstretch(1)

NAME
       pamstretch - scale up a PNM or PAM image by interpolating between pixels

SYNOPSIS
       pamstretch [-xscale=X] [-yscale=Y]
       [-blackedge] [-dropedge] N [infile]

       You  can  use the minimum unique abbreviation of the options.  You can use two hyphens in-
       stead of one.  You can separate an option name from its value with white space instead  of
       an equals sign.

DESCRIPTION
       pamstretch scales up pictures by integer values, either vertically, horizontally, or both.
       pamstretch differs from pnmscale and pnmenlarge in that when  it  inserts  the  additional
       rows  and  columns,  instead  of making the new row or column a copy of its neighbor, pam-
       stretch makes the new row or column an interpolation between its neighbors.  In  some  im-
       ages, this produces better looking output.

       To scale up to non-integer pixel sizes, e.g. 2.5, try pamstretch-gen(1) instead.

       Options  let  you select alternative methods of dealing with the right/bottom edges of the
       picture.  Since the interpolation is done between the top-left corners  of  the  scaled-up
       pixels, it's not obvious what to do with the right/bottom edges.  The default behaviour is
       to scale those up without interpolation (more precisely, the right edge is  only  interpo-
       lated  vertically,  and  the bottom edge is only interpolated horizontally), but there are
       two other possibilities, selected by the blackedge and dropedge options.

PARAMETERS
       The N parameter is the scale factor.  It is valid only if you  don't  specify  -xscale  or
       -yscale.  In that case, pamstretch scales in both dimensions and by the scale factor N.

OPTIONS
       -xscale=X
              This  is  the horizontal scale factor.  If you don't specify this, but do specify a
              vertical scale factor, the horizontal scale factor is 1.

       -yscale=Y
              This is the vertical scale factor.  If you don't specify this,  but  do  specify  a
              horizontal scale factor, the vertical scale factor is 1.

       -blackedge
              interpolate to black at right/bottom edges.
       -dropedge
              drop  one  (source) pixel at right/bottom edges. This is arguably more logical than
              the default behaviour, but it means producing output which is a slightly odd size.

BUGS
       Usually produces fairly ugly output for PBMs. For most PBM input you'll probably  want  to
       reduce the `noise' first using something like pnmnlfilt(1).

SEE ALSO
       pamstretch-gen(1), pnmenlarge(1), pnmscale(1), pnmnlfilt(1)

AUTHOR
       Russell Marks (russell.marks AT ntlworld.com).

                                         11 November 2001                           pamstretch(1)

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